Alkaline battery separators

Abstract

An alkaline battery separator comprising a gas-permeable sheet which contains a hydrophilic portion carrying a methacrylic/ethylene copolymer component having a crystallinity of 25% or more on at least a part of a surface of said hydrophilic portion.

What is claimed is:  
     
       1. An alkaline battery separator comprising a gas-permeable fiber sheet comprising hydrophilic fibers carrying a methacrylic/ethylene copolymer component having a crystallinity of 25% or more on at least a part of a surface of each of said hydrophilic fibers. 
     
     
       2. The alkaline battery separator according to  claim 1 , wherein a ratio of a total surface area of said methacrylic/ethylene copolymer components on said hydrophilic fibers in said fiber sheet to a total surface area of all constituent fibers contained in said fiber sheet is at least 10%. 
     
     
       3. The alkaline battery separator according to  claim 1 , wherein said fiber sheet is a member selected from the group consisting of a nonwoven fabric, a woven fabric, a knitted fabric, and a composite fabric thereof. 
     
     
       4. The alkaline battery separator according to  claim 1 , wherein said hydrophilic fiber is composed of only a methacrylic/ethylene copolymer having a crystallinity of at least 25%. 
     
     
       5. The alkaline battery separator according to  claim 1 , wherein said hydrophilic fiber is a composite fiber composed of the methacrylic/ethylene copolymer having a crystallinity of at least 25% and at least one other polymeric component. 
     
     
       6. The alkaline battery separator according to  claim 5 , wherein said composite fiber is covered with the methacrylic/ethylene copolymer having a crystallinity of at least 25% on a whole surface thereof. 
     
     
       7. The alkaline battery separator according to  claim 6 , wherein said composite fiber is a sheath-core and contains said methacrylic/ethylene copolymer component on a surface thereof. 
     
     
       8. The alkaline battery separator according to  claim 1 , wherein said fiber sheet consists essentially of said hydrophilic fibers. 
     
     
       9. The alkaline battery separator according to  claim 1 , wherein said fiber sheet contains, in addition to said hydrophilic fibers, at least one member selected from the group consisting of fine fibers having a fineness of less than 0.5 denier or less, high-strength fibers having a tensile strength of at least 5 g/denier and fusible fibers. 
     
     
       10. The alkaline battery separator according to  claim 1 , wherein said sheet is a fiber sheet containing hydrophilic resin powder materials adhered to surfaces of constituent fibers, said hydrophilic resin powder material carrying a methacrylic/ethylene copolymer component on at least a part of a surface of said powder material. 
     
     
       11. The alkaline battery separator according to  claim 1 , wherein said sheet is a microporous film containing hydrophilic portions carrrying said methacrylic/ethylene copolymer component on at least a part of a surface of said film. 
     
     
       12. The alkaline battery separator according to  claim 1 , wherein a hydrophilicity of said hydrophilic fibers is imparted or enhanced by sulfonation. 
     
     
       13. The alkaline battery separator according to  claim 12 , wherein said sheet has a sulfonation degree of 1×10 −3  to 10×10 −3.    
     
     
       14. An alkaline battery separator comprising a nonwoven fabric sheet of hydrophilic fibers carrying a methacrylic/ethylene copolymer component having a crystallinity of at least 25% on a whole surface of said hydrophilic fiber.